Field of the Invention
The present invention relates to an organic light emitting display device and a method for manufacturing the same.
Discussion of the Related Art
An organic light emitting display device is a newer type of flat panel display device which is a self light-emitting device, and has a viewing angle and contrast ratio that are better than those of a liquid crystal display (LCD) device. The organic light emitting display device is lightweight and thin because it does not need a separate back light, and has reduced power consumption. Also, the organic light emitting display device may be driven at a direct current and low voltage, has fast response speed, and especially has an advantage of lower cost with respect to manufacturing costs.
The organic light emitting display device injects electrons and holes into a light emitting layer from a cathode for electron injection and an anode for hole injection, respectively, and emits light when exciton obtained by combination of the injected electrons and holes is transited from an excited state to a ground state. At this time, the organic light emitting display device may be divided into a top emission type, a bottom emission type, and a dual emission type depending on a direction to which light is emitted, and may be divided into a passive matrix type and an active matrix type depending on a driving mode.
In case of the active matrix type, the organic light emitting display device displays an image by selectively emitting light through a selected sub pixel if a scan signal, a data signal and a power source are individually supplied to a plurality of sub pixels which are arranged in a matrix arrangement. At this time, the sub pixel includes a thin film transistor, which includes a switching thin film transistor, a driving thin film transistor and a capacitor, and an organic light emitting display device, which includes a first electrode connected to the driving thin film transistor, an organic layer and a second electrode.
Recently, a display device of high resolution product group has been requested. To realize such a display device, the number of pixels per unit area should be increased, and luminance should be more improved. However, there is limitation in current efficiency characteristic due to limitation in a structure of the organic light emitting display device, and electric and thermal stress within the device is increased in accordance with increase of current, whereby reliability is reduced.
Accordingly, studies of a method for solving structural limitation of the organic light emitting display device to realize a product of high resolution and a method for improving problems of power consumption increase, lifespan reduction, and reliability reduction have been made.